Surface treatment layer thickness measurement method

Abstract

The present invention discloses a method for measuring the thickness of a surface treatment layer, comprising the following steps: obtaining standard normal distribution curves corresponding to different metal elements in standard samples of surface treatment layers of different thicknesses, wherein the normal distribution curve represents the relationship between the element content and probability density of a certain element at a certain thickness; obtaining sample normal distribution curves corresponding to each metal element in the sample to be tested; and obtaining surface treatment layer thickness values ​​calculated based on the different metal elements in the sample to be tested based on the standard normal distribution curves corresponding to each metal element at different standard thicknesses and the sample normal distribution curves corresponding to the corresponding metal element in the sample to be tested, thereby obtaining the surface treatment layer thickness of the sample to be tested. This method can achieve rapid and non-destructive measurement of the thickness of the surface treatment layer, is not limited by the measurement area, and has no significant restrictions on the materials of the sample substrate and the surface treatment layer to be tested, thus having wide applicability.

Description

Technical Field

[0001] The invention belongs to the field of measurement technology, and particularly relates to a method for measuring the thickness of a surface treatment layer. Background Art

[0002] Among the existing surface treatment layer measurement technologies, magnetic thickness measurement, eddy current thickness measurement, and screw micrometer thickness measurement methods are usually used. However, these methods have certain limitations in actual measurement. For example, the magnetic thickness measurement method requires the substrate or surface treatment layer to be magnetic; the eddy current thickness measurement method requires the substrate and surface treatment layer to have conductive properties; and the use of a screw micrometer is only suitable for thickness measurement in the boundary area of ​​the substrate, and cannot achieve measurement of the surface treatment layer in the intermediate area. Summary of the Invention

[0003] The purpose of the present invention is to provide a method for measuring the thickness of a surface treatment layer, so as to solve the problems of limited applicability and poor versatility of existing measurement methods.

[0004] The present invention is achieved through the following technical solutions:

[0005] The method for measuring the thickness of the surface treatment layer comprises the following steps:

[0006] S01. Obtaining standard normal distribution curves corresponding to different metal elements in standard samples of surface treatment layers of different thicknesses, wherein the normal distribution curve is a curve showing the relationship between the element content and probability density of a certain element at a certain thickness;

[0007] S02. Obtain the sample normal distribution curve corresponding to each metal element of the sample to be tested;

[0008] S03. According to the standard normal distribution curve corresponding to each metal element under different standard thicknesses and the sample normal distribution curve corresponding to the corresponding metal element of the sample to be tested, the surface treatment layer thickness values ​​calculated based on different metal elements of the sample to be tested are obtained one by one to obtain the surface treatment layer thickness of the sample to be tested.

[0009] As a further improvement of the above technical solution, step S01 includes:

[0010] S011. Prepare standard samples with different thicknesses of surface treatment layers;

[0011] S012. Measure the thickness of the surface treatment layer of the standard sample;

[0012] S013. Measure the metal element content in the standard samples at different thicknesses multiple times to obtain standard normal distribution curves corresponding to different metal elements in the surface treatment layers at different thicknesses.

[0013] As a further improvement of the above technical solution, a standard normal distribution curve corresponding to all metal elements with a content of not less than 0.1% in the standard sample is obtained.

[0014] As a further improvement of the above technical solution, in step S012, a magnetic thickness gauge, an eddy current thickness gauge, and a screw micrometer are used to measure the surface treatment thickness of a specified area on the standard sample multiple times to obtain the thickness of the surface treatment layer of the standard sample.

[0015] As a further improvement of the above technical solution, the designated area is the location where the metal element content in the standard sample is measured in step S013.

[0016] As a further improvement of the above technical solution, the metal element content in the sample to be tested is measured multiple times to obtain a sample normal distribution curve corresponding to each metal element in the sample to be tested.

[0017] As a further improvement of the above technical solution, a sample normal distribution curve corresponding to all metal elements with a content of not less than 0.1% in the sample to be tested is obtained.

[0018] As a further improvement of the above technical solution, the test equipment, test method, and test parameters used to measure the metal element content in the sample to be tested are the same as the test conditions used to test the standard sample.

[0019] As a further improvement of the above technical solution, step S03 includes:

[0020] S031. Fitting the standard normal distribution curve corresponding to a certain metal element at different standard thicknesses with the sample normal distribution curve of the corresponding metal element of the sample to be tested;

[0021] S032. Obtain two standard normal distribution curves adjacent to the sample normal distribution curve on both sides, and obtain the thickness of the surface treatment layer calculated based on the metal element according to the overlapping area, mean distance, or intersection position between the sample normal distribution curve and the two standard normal distribution curves;

[0022] S033 , processing the thickness values ​​of the surface treatment layers obtained in step S032 to obtain the thickness of the surface treatment layer of the sample to be tested.

[0023] As a further improvement of the above technical solution, the thickness of the surface treatment layer is calculated according to a certain metal element in step S032, including:

[0024] Obtaining the overlap area ratio between the sample normal distribution curve and the two standard normal distribution curves, wherein the overlap area ratio is the ratio of the overlap area between the standard normal distribution curve and the sample normal distribution curve to the area of ​​the corresponding standard normal distribution curve;

[0025] When the overlap area ratio of the sample normal distribution curve and the two standard normal distribution curves is not less than 5%, the thickness of the surface treatment layer corresponding to the metal element is calculated as:

[0026]

[0027] Wherein, A is the standard thickness value corresponding to the standard normal distribution curve on the left, B is the standard thickness value corresponding to the standard normal distribution curve on the right, n1% is the overlap area ratio corresponding to the standard normal distribution curve on the left, and n2% is the overlap area ratio corresponding to the standard normal distribution curve on the right;

[0028] When the overlap area ratio of the sample normal distribution curve and the two standard normal distribution curves is less than 5%, the thickness of the surface treatment layer corresponding to the metal element is calculated as:

[0029]

[0030] Wherein, N is the average value of the element content in the sample to be tested, N1 is the average value of the element content corresponding to the standard normal distribution curve on the left, and N2 is the average value of the element content corresponding to the standard normal distribution curve on the right;

[0031] When the overlap area ratio of the sample normal distribution curve and the two standard normal distribution curves is not less than 5% on one side and less than 5% on the other side, the thickness of the surface treatment layer calculated based on the metal element is:

[0032] Obtain the intersection between the standard normal distribution curve and the sample normal distribution curve corresponding to the side where the overlapping area rate is not less than 5%, as well as the metal element content corresponding to the intersection. According to the corresponding metal element content, obtain the corresponding thickness value on the standard curve of metal element content and surface treatment layer thickness, which is the surface treatment layer thickness calculated corresponding to the metal element.

[0033] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0034] The present invention establishes a standard database for thickness measurement based on the relationship between multiple elements of the substrate and the thickness of the surface treatment layer of standard thickness. By measuring the elements of the sample to be measured to achieve the measurement of the thickness of the surface treatment layer, the thickness of the surface treatment layer can be measured quickly and non-destructively without being restricted by the measurement area. There are also not many restrictions on the materials of the substrate and the surface treatment layer of the sample to be measured, and the method has wide applicability. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings in the embodiments will be briefly introduced below. It should be understood that the following drawings only illustrate certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other relevant drawings can be obtained based on these drawings without paying any creative work.

[0036] Figure 1 It is a standard sample prepared in the embodiment of the measurement method of the present invention.

[0037] Figure 2 : This is the standard normal distribution curve corresponding to the Fe element of standard samples with different thicknesses in the embodiment of the measurement method of the present invention.

[0038] Figure 3 : This is the sample normal distribution curve corresponding to the Fe element of the sample to be measured in the embodiment of the measurement method of the present invention.

[0039] Figure 4 This is a schematic diagram of a situation in which a standard normal distribution curve and a sample normal distribution curve are fitted in an embodiment of the measurement method of the present invention.

[0040] Figure 5 This is a schematic diagram of another situation of fitting the standard normal distribution curve and the sample normal distribution curve in an embodiment of the measurement method of the present invention.

[0041] Figure 6 This is a schematic diagram of another situation of fitting the standard normal distribution curve and the sample normal distribution curve in an embodiment of the measurement method of the present invention.

[0042] Figure 7 This is the standard corresponding curve of Fe element content and surface treatment layer thickness. DETAILED DESCRIPTION

[0043] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments.

[0044] The present invention establishes a standard database for thickness measurement based on the relationship between multiple elements of the substrate and the thickness of the surface treatment layer of standard thickness. By measuring the elements of the sample to be measured to achieve the measurement of the thickness of the surface treatment layer, the thickness of the surface treatment layer can be measured quickly and non-destructively without being restricted by the measurement area. There is no restriction on the materials of the substrate and the surface treatment layer of the sample to be measured. It only needs to contain metal elements to be measured using this method.

[0045] In one embodiment, the surface treatment layer thickness measurement method comprises the following steps:

[0046] S01. Surface treatment is performed on the surface of a known metal matrix material according to normal product manufacturing processes to produce multiple standard samples with different surface treatment layers. The thickness of the surface treatment layer in the standard samples is generally not less than 5 μm, and the surface treatment layer thickness of each standard sample should generally cover the upper and lower thickness limits of the required test thickness. A portion of the standard sample should generally be left untreated for identification of the metal matrix material.

[0047] Clean the surface treatment layer of the standard sample and measure its thickness. Standard measuring tools such as magnetic thickness gauges, eddy current thickness gauges, and micrometers can be used for this measurement. Repeated multi-point measurements are performed on a designated area of ​​the standard sample, typically the area where the metal element is measured. Calculate the standard mean and standard deviation of the thickness measurements. The number of measurements should be no less than seven per point. If the measured data fluctuates significantly, increase the number of measurements.

[0048] X-ray fluorescence spectrometer was used to measure the metal element content of standard samples with different surface treatment layer thicknesses. Multiple measurements were performed in the designated area. The measured values ​​of all metal elements with a content of ≥ 0.1% were recorded, and their standard average and standard deviation were calculated respectively.

[0049] Based on the thickness of the surface treatment layer of the standard samples obtained from the above measurements and the corresponding measured values ​​of different metal elements in each standard sample, a standard normal distribution curve corresponding to each different metal element in the standard samples with different surface treatment layer thicknesses was established. The abscissa of the normal distribution curve represents the percentage content of the element, and the ordinate represents the probability density of the measured value. This forms a standard database corresponding to different metal elements in the standard samples with different surface treatment layer thicknesses. The probability density here refers to the number of times the same measurement value is obtained when multiple measurements are performed.

[0050] S02. Measure the metal element content of the sample to be tested. The test equipment, test mode and test process parameters used in the measurement are exactly the same as those used when measuring the standard sample. The number of measurements is generally not less than 5 times / point. Record the measured values ​​of all metal elements with a content ≥ 0.1%, and calculate their standard mean and standard deviation respectively.

[0051] Based on the measured values, the sample normal distribution curve corresponding to each metal element in the sample to be tested is obtained.

[0052] S03. According to the standard normal distribution curve corresponding to each metal element under different standard thicknesses and the sample normal distribution curve corresponding to the corresponding metal element of the sample to be tested, the surface treatment layer thickness values ​​calculated based on different metal elements of the sample to be tested are obtained one by one to obtain the surface treatment layer thickness of the sample to be tested.

[0053] In this step, the standard normal distribution curve corresponding to a certain metal element under different standard thicknesses is fitted with the sample normal distribution curve of the metal element corresponding to the sample to be tested; then, two standard normal distribution curves adjacent to the two sides of the sample normal distribution curve are obtained, and the surface treatment layer thickness value calculated by the metal element is obtained based on the overlapping area or mean distance or intersection position between the sample normal distribution curve and the two standard normal distribution curves; finally, the obtained surface treatment layer thickness values ​​are processed to obtain the surface treatment layer thickness of the sample to be tested.

[0054] The measuring method of the present invention will be further described below with reference to specific embodiments.

[0055] 1) According to the normal product manufacturing process, the surface of the known metal substrate (30CrMnSiA) was treated with surface treatment (D.Cd) to obtain three standard samples with thickness ranges of 5-12um, 12-18um, and 18-25um. The back of the standard samples was not treated with surface treatment and was used for subsequent metal substrate composition testing. The prepared standard samples are as follows: Figure 1 shown.

[0056] 2) Use acetone to wipe and clean the surface of the standard sample to remove surface contaminants that may affect the analysis. Use a coating thickness gauge to perform multiple repeated multi-point thickness measurements on the specified area of ​​the standard sample, and calculate the standard average and standard deviation obtained from the measurements.

[0057] The calculation formula for the standard average value is:

[0058] x i is the i-th measurement value;

[0059] The formula for calculating the standard deviation is:

[0060]

[0061] 3) Measure the metal element content of the standard sample using an X-MET7500 X-ray fluorescence spectrometer, selecting the Alloy LE mode and the test process parameters (conventional focus test). Measure eight times per point. Record the measured values ​​of metal elements (e.g., Fe, Cr, Mn, Cd, and Co) with a content ≥ 0.1% in the substrate with the surface treatment layer, and calculate the standard mean and standard deviation.

[0062] 4) Use Minitab software to draw the standard normal distribution curve corresponding to each metal element of the standard sample, as shown in the figure below: Figure 2 The figure shows the normal distribution curve of Fe element corresponding to surface treatment layers of different thicknesses. The horizontal axis of the curve is the percentage content of the element, and the vertical axis is the probability density of the measured value, forming a standard database corresponding to different metal elements in standard samples corresponding to surface treatment layers of different thicknesses.

[0063] 5) Measure the metal element content of the sample to be tested. The test equipment, test mode and test process parameters used in the measurement are exactly the same as those used when measuring the standard sample. The number of measurements is 8 times / point. Record the measured values ​​of metal elements such as Fe, Cr, Mn, Cd, Co, etc., and calculate their standard average value and standard deviation.

[0064] 6) Use Minitab software to draw the normal distribution curve of each metal element in the test sample, such as Figure 3 It is the normal distribution curve of the Fe element content corresponding to the test sample. Similarly, the horizontal axis of the curve is the percentage content of the element, and the vertical axis is the probability density of the measured value.

[0065] 7) Fit the sample normal distribution curve of each element of the sample to be tested with the standard normal distribution curve of each element of the standard sample of different thicknesses, and fit them into the same coordinate system to form a set of sample normal distribution curves and standard normal distribution curves corresponding to different elements, such as Figure 4 The figure shows the situation where the sample normal distribution curve and the standard normal distribution curve corresponding to the Fe element are fitted into the same coordinate system;

[0066] Select two standard normal distribution curves adjacent to the sample normal distribution curve on both sides for analysis, such as Figure 4 As shown, the overlap area ratio or mean distance between the overlap area of ​​the sample normal distribution curve and the two selected standard normal distribution curves is calculated to obtain the calculated surface treatment layer thickness corresponding to the metal element. Specifically, the calculation method used is as follows:

[0067] Taking Fe as an example, the overlap area ratio between the corresponding sample normal distribution curve and the two standard normal distribution curves is calculated.

[0068] When the overlap area ratio of the sample normal distribution curve and the two standard normal distribution curves is not less than 5%, Figure 4 The thickness of the surface treatment layer corresponding to the metal element is calculated according to the overlap area ratio, and the calculation formula used is:

[0069]

[0070] Among them, A is the standard thickness value corresponding to the standard normal distribution curve on the left, B is the standard thickness value corresponding to the standard normal distribution curve on the right, n1% is the overlapping area ratio corresponding to the standard normal distribution curve on the left, and n2% is the overlapping area ratio corresponding to the standard normal distribution curve on the right.

[0071] When the overlap area ratio of the sample normal distribution curve and the two standard normal distribution curves is less than 5%, Figure 5 The thickness of the surface treatment layer corresponding to the metal element is calculated according to the mean spacing, and the calculation formula is:

[0072]

[0073] Wherein, N is the average value of the element content of the sample to be tested, N1 is the average value of the element content corresponding to the standard normal distribution curve on the left, and N2 is the average value of the element content corresponding to the standard normal distribution curve on the right.

[0074] When the overlap area ratio of the sample normal distribution curve and the two standard normal distribution curves is not less than 5% on one side and less than 5% on the other side, Figure 6 , the calculated thickness of the surface treatment layer corresponding to the metal element is:

[0075] Obtain the intersection point between the standard normal distribution curve and the sample normal distribution curve corresponding to the side where the overlap area rate is not less than 5% ( Figure 6 The midpoint A) and the Fe element content value corresponding to the intersection point in the coordinate system are as follows: Figure 6 The Fe content corresponding to midpoint A is 36%;

[0076] Then, the Fe element content and the surface treatment layer thickness standard corresponding curve (such as Figure 7 ), obtain the Fe element content corresponding to point A on the Fe element content curve, then draw a vertical line from the point at the corresponding position on the Fe element content curve, and obtain the intersection of the vertical line and the thickness curve (point B). The thickness value corresponding to point B (in Figure 7 For example, the thickness value corresponding to point B is 10μm), which is the thickness of the surface treatment layer calculated based on the Fe element.

[0077] The standard curve of metal element content and surface treatment layer thickness is drawn based on the data of metal element content corresponding to surface treatment layers of different standard thicknesses obtained by testing. Taking Fe as an example, the following table shows the data corresponding to the measured Fe element content and surface treatment layer thickness:

[0078]

[0079] Draw a dual-axis curve based on the data table obtained from the above measurement, such as Figure 7 As shown in the figure, the left side of the vertical axis corresponds to the Fe element content, and the right side of the vertical axis corresponds to the surface treatment layer thickness. The above table only provides a portion of the measurement data. In actual operation, the amount of measurement data will be much larger, and the more measurement data, the smoother the curve will be.

[0080] 8) Repeat step 7) to obtain the calculated surface treatment layer thickness values ​​corresponding to other elements. Based on the calculated surface treatment layer thickness values ​​Ti, the surface treatment layer thickness of the sample to be tested is calculated using the following formula:

[0081]

[0082] At this point, the thickness of the surface treatment layer of the sample to be tested can be obtained.

[0083] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any form. Any simple modification or equivalent change made to the above embodiment based on the technical essence of the present invention shall fall within the scope of protection of the present invention.

Claims

1. A method for measuring the thickness of a surface treatment layer, characterized in that: The following steps are involved: S01. Obtaining standard normal distribution curves corresponding to different metal elements in standard samples of surface treatment layers of different thicknesses, wherein the normal distribution curve is a curve showing the relationship between the element content and probability density of a certain element at a certain thickness; S02. Obtain the sample normal distribution curve corresponding to each metal element of the sample to be tested; S03. According to the standard normal distribution curve corresponding to each metal element under different standard thicknesses and the sample normal distribution curve corresponding to the corresponding metal element of the sample to be tested, the surface treatment layer thickness values ​​calculated based on different metal elements of the sample to be tested are obtained one by one to obtain the surface treatment layer thickness of the sample to be tested.

2. The method for measuring the thickness of the surface treatment layer according to claim 1, characterized in that: Step S01 includes: S011. Prepare standard samples with different thicknesses of surface treatment layers; S012. Measure the thickness of the surface treatment layer of the standard sample; S013. Measure the metal element content in the standard samples at different thicknesses multiple times to obtain standard normal distribution curves corresponding to different metal elements in the surface treatment layers at different thicknesses.

3. The method for measuring the thickness of the surface treatment layer according to claim 1 or 2, characterized in that: Obtain the standard normal distribution curve corresponding to all metal elements with a content of not less than 0.1% in the standard sample.

4. The method for measuring the thickness of the surface treatment layer according to claim 2, wherein: In step S012, a magnetic thickness gauge, an eddy current thickness gauge, and a screw micrometer are used to measure the surface treatment thickness of a designated area on the standard sample multiple times to obtain the thickness of the surface treatment layer of the standard sample.

5. The method for measuring the thickness of the surface treatment layer according to claim 4, characterized in that: The designated area is the location where the metal element content in the standard sample is measured in step S013.

6. The method for measuring the thickness of the surface treatment layer according to claim 1, characterized in that: The metal element content in the sample to be tested is measured multiple times to obtain the sample normal distribution curve corresponding to each metal element in the sample to be tested.

7. The method for measuring the thickness of the surface treatment layer according to claim 1 or 6, characterized in that: Obtain the sample normal distribution curve corresponding to all metal elements with a content of not less than 0.1% in the sample to be tested.

8. The method for measuring the thickness of the surface treatment layer according to claim 6, wherein: The test equipment, test method, and test parameters used to measure the metal element content in the sample to be tested are the same as the test conditions used to test the standard sample.

9. The method for measuring the thickness of the surface treatment layer according to claim 1, wherein: Step S03 includes: S031. Fitting the standard normal distribution curve corresponding to a certain metal element at different standard thicknesses with the sample normal distribution curve of the corresponding metal element of the sample to be tested; S032. Obtain two standard normal distribution curves adjacent to the sample normal distribution curve on both sides, and obtain the thickness of the surface treatment layer calculated based on the metal element according to the overlapping area, mean distance, or intersection position between the sample normal distribution curve and the two standard normal distribution curves; S033 , processing the thickness values ​​of the surface treatment layers obtained in step S032 to obtain the thickness of the surface treatment layer of the sample to be tested.

10. The method for measuring the thickness of the surface treatment layer according to claim 9, characterized in that: In step S032, the thickness of the surface treatment layer is calculated according to a certain metal element, including: Obtaining the overlap area ratio between the sample normal distribution curve and the two standard normal distribution curves, wherein the overlap area ratio is the ratio of the overlap area between the standard normal distribution curve and the sample normal distribution curve to the area of ​​the corresponding standard normal distribution curve; When the overlap area ratio of the sample normal distribution curve and the two standard normal distribution curves is not less than 5%, the thickness of the surface treatment layer corresponding to the metal element is calculated as: Wherein, A is the standard thickness value corresponding to the standard normal distribution curve on the left, B is the standard thickness value corresponding to the standard normal distribution curve on the right, n1% is the overlap area ratio corresponding to the standard normal distribution curve on the left, and n2% is the overlap area ratio corresponding to the standard normal distribution curve on the right; When the overlap area ratio of the sample normal distribution curve and the two standard normal distribution curves is less than 5%, the thickness of the surface treatment layer corresponding to the metal element is calculated as: Wherein, N is the average value of the element content in the sample to be tested, N1 is the average value of the element content corresponding to the standard normal distribution curve on the left, and N2 is the average value of the element content corresponding to the standard normal distribution curve on the right; When the overlap area ratio of the sample normal distribution curve and the two standard normal distribution curves is not less than 5% on one side and less than 5% on the other side, the thickness of the surface treatment layer calculated based on the metal element is: Obtain the intersection between the standard normal distribution curve and the sample normal distribution curve corresponding to the side where the overlapping area rate is not less than 5%, as well as the metal element content corresponding to the intersection. According to the corresponding metal element content, obtain the corresponding thickness value on the standard curve of metal element content and surface treatment layer thickness, which is the surface treatment layer thickness calculated corresponding to the metal element.

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